Specify values file for release jobs

Change-Id: Ib581a03847e34c9cb0a3519c3f581840ec52e06d
(cherry picked from commit 4f23d9d258bbbdc4c22841ade4328c3acfcfe9fe)
diff --git a/Jenkinsfile-voltha-build b/Jenkinsfile-voltha-build
index 98cbb0f..1c8b38a 100644
--- a/Jenkinsfile-voltha-build
+++ b/Jenkinsfile-voltha-build
@@ -88,12 +88,14 @@
                     sh returnStdout: true, script: """
                     export KUBECONFIG=$WORKSPACE/${configBaseDir}/${configKubernetesDir}/${configFileName}.conf
                     cd kind-voltha/
+                    export EXTRA_HELM_FLAGS=""
                     if [ "${branch}" != "master" ]; then
                         cd $WORKSPACE/kind-voltha
+                        # The releases/ file also specifies EXTRA_HELM_FLAGS
                         source releases/${branch}
-                    else
-                        export EXTRA_HELM_FLAGS='-f $WORKSPACE/${configBaseDir}/${configKubernetesDir}/voltha/${configFileName}.yml'
                     fi
+                    # Make sure that the EXTRA_HELM_FLAGS from the releases/ file appear at the end to override earlier values
+                    export EXTRA_HELM_FLAGS="-f $WORKSPACE/${configBaseDir}/${configKubernetesDir}/voltha/${configFileName}.yml \$EXTRA_HELM_FLAGS"
 
                     # JENKINS_NODE_COOKIE=dontKillMe ask Jenkins doesn't kill the proces after this job.
                     # we want the `while true; do kubectl port-forward` keep alive